The report, 'Alone with my thoughts', includes a survey by YouGov of over 2000 young people* which reveals that nearly a 29% have self-harmed because they feel 'down'.

And more than half of those who had shown signs of depression as children felt let down by their experiences of mental health support.

On average, those children who showed symptoms of depression and talked to more than one person, ended up speaking to people a shocking 22 times before they got help.

Almost half of young people with depression never got the help they wanted.

Emma-Jane Cross, CEO and founder of MindFull (which is part of The BB Group) said: "Too many children who try to speak out about the way they're feeling are being let down or simply ignored.

"It's unacceptable that so many are having to resort to harming themselves on purpose in order to cope, or worse still are thinking about ending their own lives.

"Early intervention is proven to help prevent adult mental health problems, so swift action must be taken now if we are to avoid a legacy of serious long-term mental illness.

"MindFull is a direct result of the feedback that we have been given by thousands of young people in the UK, who tell us they want the flexibility and convenience of an online service."

MindFull will give children and teenagers the support of mental health professionals and enable them to mentor one another in a safe space.

The charity will also educate young people about how to cope with mental health issues – providing information, advice and guidance, both online and through training in schools.

Professor Tanya Byron, President of The BB Group and Chartered Clinical Psychologist said: "Just as we look after our children's physical health, it's vital that we also offer support for their mental wellbeing.

"Children and young people are clearly not getting the help they need, that's why this new online support from MindFull is so important.

"Teenagers naturally look to the internet as a source of information and advice, so that's where we need to be in order to help the hundreds of thousands of young people who are currently getting no support."

The survey also reinforces the need for more information and training in schools. Nearly two thirds of young people believe adding information on mental health to the national curriculum and training teachers would be effective ways to tackle the problem.

MindFull is calling for mental health to be embedded as a core theme in the national curriculum and for schools to provide access to counselling and mentor support for all young people who need it.

'Don't dismiss how I'm feeling as teenage angst'

Jessica was 14 when she started to feel very down. She didn't tell anyone about the way she was feeling until she was 15, and even though she started to have suicidal thoughts it took her six months before she was able to talk to her mum and get help.

She said: "People don't understand the effect that depression has on you – I hate it when people dismiss it as simply teenage angst. Some days I feel so low it can be a struggle to do things that I normally love, like reading and writing.

"We desperately need more education about mental health issues so young people can spot the signs early.

"My generation is constantly online – it's where we look for information and advice, which is why I think a site like MindFull will make an enormous difference to all the young people who feel like they have no one to turn to."